Gotcha. I don't know how I missed that 😕 my apologies. I'm looking for the size of bolt that secures the power steering & a/c bracket to the cylinder head. Any idea where to look?

 

What motor and what year is the block / head?
I say this because sometime in the 80's I think it was the block & heads started using metric threads I believe.

If I have a threaded hole and dont know the size I find a bolt from my "stock of nuts & bolts" and see if it fits.
Then I pull out my tap & die set and match it to a die so I then know what size it is.

As a guess most likely a 3/8" SAE bolt would fit as I think 5/16" would be to small / light duty for holding anything to the front of the motor.
Dave ----